(鹽城工學院 材料工程學院，鹽城 224051)
摘 要: 對過共晶Al-20%Si合金進行變質(zhì)和合金化處理，并在不同環(huán)境溫度下進行摩擦磨損測試。結果表明，經(jīng)過Cu-P中間合金變質(zhì)后的初晶Si相和共晶Si相明顯細化和鈍化，再添加1.5%Zr (質(zhì)量分數(shù))后初晶Si相的粒徑更小，為20~40 μm，且趨于球形。共晶Si相呈纖維狀或短棒狀，長度明顯變短(≤50 μm)。以上3種合金隨環(huán)境溫度的升高都出現(xiàn)了從輕微磨損到嚴重磨損的轉(zhuǎn)變，且轉(zhuǎn)變載荷隨環(huán)境溫度的升高而減小。室溫下3種合金的磨損曲線差異不大，但在較高的環(huán)境溫度下，經(jīng)變質(zhì)和合金化處理后，發(fā)生磨損轉(zhuǎn)變的載荷明顯減小，細化的初晶和共晶Si相提高了合金的性能，特別是高溫耐磨性能。這歸因于細化的Si相避免了應力集中和磨損過程中的直接破碎化，在高溫磨損階段磨損表面易形成機械混合層，阻礙合金與對磨副的直接接觸，降低磨損率。
關鍵字: 過共晶Al-Si合金；變質(zhì)處理；合金化；摩擦；磨損
（School of Materials Engineering, Yancheng Institute of Technology, Yancheng 224051, China）
Abstract:The hypereutectic Al-20%Si alloy was treated by modification and alloying. The wear tests were conducted under various ambient temperatures. The results show that after modification of Cu-P master alloy, the primary and eutectic Si phases are significantly refined and passivated. After adding 1.5%Zr (mass fraction) again, the shape of primary Si becomes spherical and the particle size becomes smaller, being 20-40 μm; a fibrous or short rod shape eutectic Si phase forms in the modified alloy, the length is less than 50 μm. The mild-to-severe wear transition occurs with increasing the load, and the critical loads reduce with rising the ambient temperature for the three aluminum alloys. The changing trend of wear curves of three alloys is similar at room temperature, but the critical loads of wear transition reduce after the modification and alloying at high ambient temperatures. The refinement of primary and eutectic Si phase obviously increases the alloy performance, especially the wear resistance at elevated temperature. This is attributed to the refined Si phase avoiding the stress concentration and direct fragmentation during wear process. And mechanical mixed layer is very easy to form in the elevated temperature wear process, which hinders the direct contact between the alloy and the counterface and decreases the wear rate.
Key words: hypereutectic Al-Si alloy; modification; alloying; friction; wear
